Cross Connection and Backflow Protection

YCUA delivers drinking water through a series of pipes (transmission mains and distribution mains) to our customers. Once the clean water is delivered through the water meters to you, this same water cannot return back into the drinking water supply. Existing or potential connections between potable (safe to drink) and non-potable water supplies are a serious potential public health hazard.

Most contaminated water from homes and businesses passes into the wastewater collection system. Unfortunately, the water sometimes reverses direction back through the water meter. This reversal of direction is called a backflow. An example of a potential backflow source is a common garden hose submerged in a swimming pool, a bucket of detergent, or other contaminated water. Other examples are supply lines connected to boilers, process equipment, or bottom-fed tanks.

The point in a plumbing system where a backflow occurs is referred to as a cross-connection. Cross-connection control is an essential component of any safe drinking water system and properly installed and maintained backflow prevention devices are crucial in the control of waterborne disease outbreaks in our communities and workplaces.

There are two ways that contaminated water can backflow into the drinking water supply:BackflowPrevention1

  1. Backsiphonage - A sudden loss of water pressure caused by a broken water main or a fire hydrant in use.
  2. Backpressure - A condition caused when downstream pressure exceeds upstream pressure.
The five basic methods that are used to protect against backflow are:

  1. Air Gap - A method calling for a minimum of two inches of space between your home's hose spigot and a container of contaminated water.
  2. Atmospheric and Hose Connection Vacuum Breaker - A device that attaches to a hose spigot. The breaker allows normal water flow to come through the spigot but will close if any backflow occurs.
  3. Pressure Type Vacuum Breaker - A device primarily used for residential and commercial sprinkling systems.
  4. Double Check Valve Assembly - A device used primarily for fire protection systems only.
  5. Reduced Pressure Principle Backflow Preventer - A device used to provide maximum protection from health hazard cross-connection.
With the exception of the standard hose connection vacuum breaker, all devices should be installed and tested by a certified backflow prevention tester. Contact YCUA at 734-484-4600 ext. 312 for a listing of certified testers or for any other information regarding cross-connection and backflow prevention. Most devices can be obtained at your local hardware and home improvement stores.

Incidents have occurred where the backflow of contaminated water through a cross-connection has been the agent for contaminating a community's drinking water system, resulting in illness, the spread of disease, and death, along with severe economic repercussions.

The cross-connection problem is an ongoing one, because potable water piping systems are continually being installed and altered, while water using devices and equipment which can contaminate a drinking water system often are connected to potable waterlines without appropriate, properly installed backflow prevention equipment.

For more information on cross-connection, you may wish to visit the following web sites:

If you are concerned that an existing or potential cross-connection exists in your home or place of business and would like more information on backflow prevention equipment and installation, please contact YCUA's Cross-Connection Control and Backflow Prevention Supervisor Sean Knapp by telephone at 734-484-4600 ext. 325, by fax at 734-484-7541, or by e-mail at